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Authors | Guanhong Feng Tianfu Xu Yue'an Zhao Fabrizio Gherardi

Title | Heat mining from super-hot horizons of the Larderello geothermal field, Italy

Source | Renewable Energy

Edit | Geothermal Core (add micro-signal: geothermalAI, can get related information)

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01

full text guide

Geothermal energy from ultra-high temperature rocks is an emerging renewable and carbon-free energy source. In this paper, we make a first attempt to explore the fluid and heat flow dynamics in a coupled reservoir-wellbore system to evaluate the power generation performance of an ultra-high temperature (>450°C) enhanced geothermal system (EGS). We developed a high-performance code and constructed a 3D wellbore-reservoir coupling model based on data from a recently completed deep drilling project in Ladrero, Italy. The general model of an ultra-high temperature EGS exhibits a significant temperature drop (>60°C), after which the production fluid evolves from steam to a two-phase mixture until the end of the operating period. The reservoir pressure becomes a key parameter in determining the temperature of the two-phase mixture. By realistically capturing the phase change driven by coupled thermohydraulic processes during operation, our numerical model predicts lower power generation efficiencies than previous attempts based on an oversimplified model. Although this modeling approach was ultimately used to assess the thermodynamic viability of a specific system, it provides general information about the underlying thermohydraulic processes in the crust that may be applicable to the design of similar EGS projects in other regions.

In this paper, we explore the feasibility of an ultra-high temperature EGS at depth in the Radrero geothermal field, Italy, through thermohydraulic modeling. The dual objectives of the numerical simulations are (i) to gain insights into the fundamental processes of fluid and heat transport associated with the operation of deep geothermal twin wells in the mid-crust and (ii) to provide a preliminary assessment of the thermodynamic feasibility of similar projects for long-term use in the exploitation of conventional hydrothermal resources. This technical challenge responds to the need to extend the life of the Ladrero geothermal field and potentially increase its productivity in a sustainable manner.

Despite current approximations, numerical simulations reveal the fundamental thermohydraulic processes expected under supercritical geothermal conditions. This information is applicable not only to Ladrero, but also to other similar environments at mid-crustal depths, in order to define the most suitable technology to guarantee the sustainable operation of the power plant and to adapt the ground equipment/technology to the possible decrease in productivity of the geothermal twin wells. The main results are presented below:

  • Under the conditions considered in this study, the geothermal twin wells produce steam phases for approximately ten years. At an operating mass flow rate of 12.5 kg/s, up to 6.5 MWe of electricity can be generated, with a corresponding generation efficiency of 0.52 MWe × s × kg-1, which is not as high as previously calculated by the oversimplified model.
  • A sharp drop in outflow temperature greater than 60°C is predicted at the onset of the two-phase condition, caused primarily by the difference between the saturation temperature and the original reservoir temperature. After that, the outflow presents as a two-phase mixture for the remainder of the operating period, with its temperature determined by the reservoir pressure;
  • Reservoir pressure becomes a key factor in controlling the thermohydraulic evolution of the system because pressure can determine the timing of the phase transition and the outflow temperature. In general, higher reservoir pressures are beneficial in offsetting temperature drops and improving fluid flow;
  • Ultra-high temperature EGS projects require compensatory injection schemes. Injection and production flow rates need to be carefully optimized to reduce friction losses that may adversely affect wellhead pressures and temperatures, thereby affecting the overall energy conversion process.

02

HIGHLIGHT Pictures

Fig. 1 . Location map of the Larderello geothermal field (a) and temperature vs depth diagram of temperature values measured along the vertical profile of the Venelle 2 well (empty squares; b). Curves for temperature (T, red), pressure (P, blue), and steam saturation (S steam , green) calculated values are also provided (more details in the (more details in the Supplementary Materials).

Fig. 2 . 3-D and X-Z 2-D view of the conceptual model of fractured reservoir.

Fig. 3 . Pressure, temperature, and steam saturation evolution at two observational points located at the top and the bottom of the fractured reservoir, along (a) Patterns over 100 years production. (b) Detail of first 17 years production.

Fig. 4 . Temperature, pressure and steam saturation along the line connecting the bottom hole of the injection (point "a") and production (point "d") wells after two selected times (3.7 and 6.5 years) close to the second temperature drop. Temperature, pressure and steam saturation along the line connecting the bottom hole of the injection (point "a") and production (point "d") wells after two selected times (3.7 and 6.5 years) close to the second temperature drop. Points marked "b" (x coordinate -120 m) and "c" (x coordinate +20 m) locate at intermediate The two wells are located at intermediate distances between the two wells.

Fig. 5 . Temperature and steam saturation distribution along the X-Z cross-section connecting the injection and production wells after 30 years.

Fig. 6 . (a) Pressure, temperature, and steam saturation evolution at the production wellhead; (b) production flow rate and recovery percentage of injected water.

Fig. 7 . Pressure (a), temperature (b), steam saturation (c), and mixture density (d) evolution in the production well.

Fig. 8 . Fluid specific enthalpy (kJ/kg) range of currently operating geothermal power plants (modified after [ 57 ]).

Fig. 9 . Temporal evolution of heat flow (a), thermal and power generation, and conversion efficiency (b).

Fig. 10 . Temporal evolution of heat flow (a), thermal and power generation, and conversion efficiency (b) for different permeability cases.

Fig. 11 . Pressure (a) and temperature (b) patterns at the production wellhead under different conditions of fracture permeability.

Fig. 12 . Contribution of different mechanisms to the pressure change for different permeability values after 3.5 and 20 years.

Fig. 13 . Phase mobility contours under different pressure and temperature conditions.

Disclaimer: This article is for academic communication and dissemination only, and does not constitute investment advice

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References:

[1]
G.Ó. Friðleifsson, W.A. Elders
The Iceland Deep Drilling Project: a search for deep unconventional geothermal resources
Geothermics, 34 (3) (2005), pp. 269-285, 10.1016/j.geothermics.2004.11.004
View PDFView articleView in ScopusGoogle Scholar

[2]
G.Ó. Friðleifsson, W.A. Elders, A. Albertsson
The concept of the Iceland deep drilling project
Geothermics, 49 (2014), pp. 2-8, 10.1016/j.geothermics.2013.03.004
View PDFView articleGoogle Scholar

[3]
H. Asanuma, H. Muraoka, N. Tsuchiya, H. Ito
The concept of the Japan Beyond-Brittle Project (JBBP) to develop EGS reservoirs in ductile zones
GRC Transactions, 36 (2012), pp. 359-364
View in ScopusGoogle Scholar

[4]
T.T. Cladouhos, S. Petty, A. Bonneville, A. Schultz, C.F. Sorlie
Super Hot EGS and the Newberry Deep Drilling Project
(2018)
Google Scholar

[5]
G. Bignall
Hotter and deeper: New Zealand's research programme to harness its deep geothermal resources
Proc. World Geoth. Cong. (2010)
Google Scholar

[6]
F. Batini, P.D. Burgassi, G.M. Cameli, R. Nicolich, P. Squarci
Contribution to the Study of the Deep Lithospheric Profiles: "deep" Reflecting Horizons in Larderello-Travale Geothermal Field
(1978)
Google Scholar

[7]
F. Batini, G. Bertini, G. Gianelli, E. Pandeli, M. Puxeddu
Deep structure of the Larderello field: contribution from recent geophysical and geological data
Soc. Geol. Ital. Mem., 25 (1983), pp. 219-235
Google Scholar

[8]
F. Batini, R. Nicolich
P and S reflection seismic profiling and well logging in the travale geothermal field
Geothermics, 14 (5) (1985), pp. 731-747, 10.1016/0375-6505(85)90049-5
View PDFView articleView in ScopusGoogle Scholar

[9]
R Bertani, H Büsing, S Buske, A Dini, M Hjelstuen, M Luchini, et al.
The first results of the Descramble project
Proc. 43rd Workshop on Geothermal Reservoir Engineering, Stanford, California, February 12-14, 2018 (2018)
SGP-TR-213, 16 pp
Google Scholar

[10]
G. Magro, F. Gherardi, G. Giudetti, M. Costantino, E. Carcione
DESCRAMBLE project: gas logging while drilling the Venelle_2 geothermal well (Larderello, Italy)
Proceedings of the World Geothermal Congress 2020+1 (2021)
Reykjavik, Iceland, April-October
Google Scholar

[11]
G. Magro, E. Droghieri, F. Gherardi
Drilling super-hot horizons of the Larderello geothermal field: insights from noble gases
E3S Web Conf., 98 (2019), Article 12012
CrossRefView in ScopusGoogle Scholar

[12]
K. Pruess, C. Oldenburg, G. Moridis
TOUGH2 User's Guide, Version 2.0. Report LBNL-43134
Lawrence Berkeley National Laboratory, Berkeley, Calif (1999)
Google Scholar

[13]
G. Lavecchia, F. Stoppa
The Tyrrhenian zone: a case of lithosphere extension control of intra-continental magmatism
Earth Planet Sci. Lett., 99 (4) (1990), pp. 336-350, 10.1016/0012-821X(90)90138-N
View PDFView articleView in ScopusGoogle Scholar

[14]
G. Serri, F. Innocenti, P. Manetti
Geochemical and petrological evidence of the subduction of delaminated Adriatic continental lithosphere in the genesis of the Neogene-Quaternary magmatism of central Italy
Tectonophysics, 223 (1) (1993), pp. 117-147, 10.1016/0040-1951(93)90161-C
View PDFView articleView in ScopusGoogle Scholar

[15]
L. Carmignani, F.A. Decandia, P.L. Fantozzi, A. Lazzarotto, D. Liotta, M. Meccheri
Tertiary extensional tectonics in Tuscany (Northern Apennines, Italy)
Tectonophysics, 238 (1) (1994), pp. 295-315, 10.1016/0040-1951(94)90061-2
View PDFView articleView in ScopusGoogle Scholar

[16]
L. Jolivet, J.M. Daniel, C. Truffert, B. Goffé
Exhumation of deep crustal metamorphic rocks and crustal extension in arc and back-arc regions
Lithos, 33 (1) (1994), pp. 3-30, 10.1016/0024-4937(94)90051-5
View PDFView articleView in ScopusGoogle Scholar

[17]
R.D. Dallmeyer, D. Liotta
Extension, uplift of rocks and cooling ages in thinned crustal provinces: the Larderello geothermal area (inner Northern Apennines, Italy)
Geol. Mag., 135 (2) (1998), pp. 193-202, 10.1017/S0016756898008309
View in ScopusGoogle Scholar

[18]
B. Della Vedova, S. Bellani, G. Pellis, P. Squarci
Deep temperatures and surface heat flow distribution
G.B. Vai, I.P. Martini (Eds.), Anatomy of an Orogen: the Apennines and Adjacent Mediterranean Basins, Springer Netherlands, Dordrecht (2001), pp. 65- 76
Google Scholar

[19]
S. Bellani, A. Brogi, A. Lazzarotto, D. Liotta, G. Ranalli
Heat flow, deep temperatures and extensional structures in the Larderello Geothermal Field (Italy): constraints on geothermal fluid flow
J. Volcanol. Geoth. Res., 132 (1) (2004), pp. 15-29, 10.1016/S0377-0273(03)00418-9
View PDFView articleView in ScopusGoogle Scholar

[20]
G. Bertini, M. Casini, G. Gianelli, E. Pandeli
Geological structure of a long-living geothermal system
Larderello, Italy. Terra Nova., 18 (3) (2006), pp. 163-169, 10.1111/j.1365-3121.2006.00676.x
View in ScopusGoogle Scholar

[21]
G.M. Cameli, I. Dini, D. Liotta
Upper crustal structure of the Larderello geothermal field as a feature of post-collisional extensional tectonics (Southern Tuscany, Italy)
Tectonophysics, 224 (4) (1993), pp. 413-423, 10.1016/0040-1951(93)90041-H
View PDFView articleView in ScopusGoogle Scholar

[22]
G. Cameli
Brittle/ductile boundary from seismic reflection lines of southern Tuscany (Northern Apennines, Italy)
Mem. Soc. Geol. It, 52 (1998), pp. 153-162
Google Scholar

[23]
F. Batini, G. Bertini, G. Gianelli, E. Pandeli, M. Puxeddu, I. Villa
Deep structure, age and evolution of the Larderello-Travale geothermal field
GRC Transactions, 9 (1985), pp. 253-259
View in ScopusGoogle Scholar

[24]
B.L. Cox, K. Pruess
Numerical experiments on convective heat transfer in water saturated porous media at near-critical conditions
Transport Porous Media, 5 (3) (1990), pp. 299-323
View in ScopusGoogle Scholar

[25]
W.M. Kissling
Extending MULKOM to super-critical temperatures and pressures
Proc. WGC 1995 (1995), pp. 1687-1690
Firenze, Italy
Google Scholar

[26]
T.H. Brikowski
Modeling supercritical systems with TOUGH2: preliminary results using the EOS1SC equation of state module
Proc. 26th Work. Geoth. Res. Eng, Stanford University, Stanford, CA (2001)
Google Scholar

[27]
A.E. Croucher, M.J. O'Sullivan
Application of the computer code TOUGH2 to the simulation of supercritical conditions in geothermal systems
Geothermics, 37 (2008), pp. 622-634, 10.1016/j.geothermics.2008.03.005
View PDFView articleView in ScopusGoogle Scholar

[28]
L. Magnusdottir, S. Finsterle
An iTOUGH2 equation-of-state module for modeling supercritical conditions in geothermal reservoirs
Geothermics, 57 (2015), pp. 8-17, 10.1016/j.geothermics.2015.05.003
View PDFView articleView in ScopusGoogle Scholar

[29]
W.M. Kissling
Transport of three-phase hyper-saline brines in porous media: theory and code implementation
Transport Porous Media, 61 (2005), pp. 25-44
CrossRefView in ScopusGoogle Scholar

[30]
R. McKibbin, A. McNabb
Deep hydrothermal systems: mathematical modeling of hot dense brines containing noncondensible gases
J. Porous Media, 2 (1) (1999), pp. 107-126
View in ScopusGoogle Scholar

[31]
J. O'Sullivan, M.J. O'Sullivan, A. Croucher
Improvements to the AUTOUGH2 supercritical simulator with extension to the air-water equation-of-State
GRC Transactions, 40 (2016), pp. 921-930
View in ScopusGoogle Scholar

[32]
Gudmundsdottir H, Jonsson MT, Palsson H. Conference The wellbore simulator FloWell.
Google Scholar

[33]
A. Goldszal, J.I. Monsen, T.J. Danielson, K.M. Bansal, Z.L. Yang, S.T. Johansen, et al.
Ledaflow 1D: Simulation Results with Multiphase Gas/Condensate and Oil/Gas Field Data
(2007)
Google Scholar

[34]
A. Battistelli, S. Finsterle, M. Marcolini, L. Pan
Modeling of coupled wellbore-reservoir flow in steam-like supercritical geothermal systems
Geothermics, 86 (2020), Article 101793, 10.1016/j.geothermics.2019.101793
View PDFView articleView in ScopusGoogle Scholar

[35]
L. Pan, C.M. Oldenburg, Y.-S. Wu, K. Pruess
T2Well/ECO2N Version 1.0: Multiphase and Non-isonthermal Model for Coupled Wellbore-Reservoir Flow of Carbon Dioxide and Variable Salinity Water. LBNL-4291E
Lawrence Berkeley National Laboratory, Berkeley, Calif (2011)
Google Scholar

[36]
L. Pan, C.M. Oldenburg
T2Well-an integrated wellbore-reservoir simulator
Comput. Geosci., 65 (2014), pp. 46-55, 10.1016/j.cageo.2013.06.005
View PDFView articleView in ScopusGoogle Scholar

[37]
G. Feng, Y. Wang, T. Xu, F. Wang, Y. Shi
Multiphase flow modeling and energy extraction performance for supercritical geothermal systems
Renew. Energy, 173 (2021), pp. 442-454, 10.1016/j.renene.2021.03.107
View PDFView articleView in ScopusGoogle Scholar

[38]
G. Feng, T. Xu, F. Gherardi, Z. Jiang, S. Bellani
Geothermal assessment of the Pisa plain, Italy: coupled thermal and hydraulic modeling
Renew. energy, 111 (2017), pp. 416-427, 10.1016/j.renene.2017.04.034
View PDFView articleView in ScopusGoogle Scholar

[39]
K. Zhang, Y.S. Wu, K. Pruess
User's Guide for TOUGH2-MP -a Massively Parallel Version of the TOUGH2 Code. Report LBNL-315E
Lawrence Berkeley National Laboratory, Berkeley, Calif (2008)
Google Scholar

[40]
N. Zuber, J.A. Findlay
Average volumetric concentration in two-phase flow systems
J. Heat Tran., 87 (4) (1965), pp. 453-468
CrossRefView in ScopusGoogle Scholar

[41]
H. Shi, J.A. Holmes, L.J. Durlofsky, K. Aziz, L. Diaz, B. Alkaya, et al.
Drift-flux modeling of two-phase flow in wellbores
SPE J., 10 (2005), pp. 24-33
01
View in ScopusGoogle Scholar

[42]
J. Rutqvist, P.F. Dobson, J. Garcia, C. Hartline, P. Jeanne, C.M. Oldenburg, et al.
The northwest Geysers EGS demonstration project, California: pre-stimulation modeling and interpretation of the stimulation
Math. Geosci., 47 (1) (2015), pp. 3-29
CrossRefView in ScopusGoogle Scholar

[43]
Y. Yuan, T. Xu, J. Moore, H. Lei, B. Feng
Coupled thermo-hydro-mechanical modeling of hydro-shearing stimulation in an enhanced geothermal system in the raft river geothermal field, USA
Rock Mech. Rock Eng., 53 (12) (2020), pp. 5371-5388
CrossRefView in ScopusGoogle Scholar

[44]
A. Ebigbo, J. Niederau, G. Marquart, I. Dini, M. Thorwart, W. Rabbel, et al.
Influence of depth, temperature, and structure of a crustal heat source on the geothermal reservoirs of Tuscany: numerical modelling and sensitivity study
Geoth. Energy, 4 (1) (2016), pp. 1-29
Google Scholar

[45]
A. Morin, B.T. LØvfall, E. Meese
Simulation of Supercritical Water Flow in the Venelle 2 Well
(2016)
Google Scholar

[46]
H.J. Ramey Jr.
Wellbore heat transmission
J. Petrol. Technol., 225 (1962), pp. 427-435
View in ScopusGoogle Scholar

[47]
G.S. Bödvarsson, C.F. Tsang
Injection and thermal breakthrough in fractured geothermal reservoirs
J. Geophys. Res. Solid Earth, 87 (B2) (1982), pp. 1031-1048, 10.1029/JB087iB02p01031
View in ScopusGoogle Scholar

[48]
S.K. Garg, J.W. Pritchett
Pressure transient analysis for two-phase geothermal wells: some numerical results
Water Resour. Res., 20 (7) (1984), pp. 963-970, 10.1029/WR020i007p00963
View in ScopusGoogle Scholar

[49]
M. O'Sullivan
Aspects of geothermal well test analysis in fractured reservoirs
Transport Porous Media, 2 (5) (1987), pp. 497-517
View in ScopusGoogle Scholar

[50]
M.C. Leverett
Capillary behavior in porous solids
Trans. AIME, 142 (1941), pp. 152-169, 10.2118/941152-g
01
Google Scholar

[51]
A. Battistelli, D. Swenson, A. Alcott
Improved PetraSim-TOUGH2 capabilities for the simulation of geothermal reservoirs
Proc. 42nd Workshop on Geothermal Reservoir Engineering, Stanford, California, February 13-15, 2017 (2017)
SGP-TR-212, 14 pp
Google Scholar

[52]
H.I. Stone
Probability model for estimating three-phase relative permeability
J. Petrol. Technol., 22 (2) (1970), pp. 214-218
Google Scholar

[53]
A.T. Corey
The interrelation between gas and oil relative permeabilities
Prod. Mon., 19 (1) (1954), pp. 38-41
Google Scholar

[54]
M.T. Van Genuchten
A closed-form equation for predicting the hydraulic conductivity of unsaturated soils
Soil Sci. Soc. Am. J., 44 (44) (1980), pp. 892-898
CrossRefView in ScopusGoogle Scholar

[55]
K. Pruess
Enhanced geothermal systems (EGS) using CO2 as working fluid-a novel approach for generating renewable energy with simultaneous sequestration of carbon
Geothermics, 35 (4) (2006), pp. 351-367, 10.1016/j.geothermics.2006.08.002
View PDFView articleView in ScopusGoogle Scholar

[56]
T. Xu, Y. Yuan, X. Jia, Y. Lei, S. Li, B. Feng, et al.
Prospects of power generation from an enhanced geothermal system by water circulation through two horizontal wells: a case study in the Gonghe Basin, Qinghai Province, China Qinghai Province, China
Energy (Oxford), 148 (2018), pp. 196-207, 10.1016/j.energy.2018.01.135
View PDFView articleView in ScopusGoogle Scholar

[57]
S.J. Zarrouk, H. Moon
Efficiency of geothermal power plants: a worldwide review
Geothermics, 51 (2014), pp. 142-153, 10.1016/j.geothermics.2013.11.001
View PDFView articleView in ScopusGoogle Scholar

[58]
P. Rose, J.M. Moore, J. Bradford, M. Mella, B. Ayling, J. McLennan
Tracer testing to characterize hydraulic stimulation experiments at the raft river EGS demonstration site
GRC Transactions, 41 (2017)
26-6
Google Scholar

[59]
B. Sanjuan, J.-L. Pinault, P. Rose, A. Gérard, M. Brach, G. Braibant, et al.
Tracer testing of the geothermal heat exchanger at Soultz-sous-Forêts (France) between 2000 and 2005
Geothermics, 35 (5) (2006), pp. 622-653, 10.1016/j.geothermics.2006.09.007
View PDFView articleView in ScopusGoogle Scholar

[60]
B.F. Ayling, R.A. Hogarth, P.E. Rose
Tracer testing at the Habanero EGS site, central Australia
Geothermics, 63 (2016), pp. 15-26, 10.1016/j.geothermics.2015.03.008
View PDFView articleView in ScopusGoogle Scholar

[61]
R. Egert, M.G. Korzani, S. Held, T. Kohl
Implications on large-scale flow of the fractured EGS reservoir Soultz inferred from hydraulic data and tracer experiments
Geothermics, 84 (2020), Article 101749, 10.1016/j.geothermics.2019.101749
View PDFView articleView in ScopusGoogle Scholar

[62]
T. Xu, X. Liang, Y. Xia, Z. Jiang, F. Gherardi
Performance evaluation of the Habanero enhanced geothermal system, Australia: optimization based on tracer and induced micro-seismicity data
Renew. Energy, 181 (2022), pp. 1197-1208, 10.1016/j.renene.2021.09.111
View PDFView articleView in ScopusGoogle Scholar

[63]
J.P. Brill, H.K. Mukherjee
Multiphase Flow in Wells
Society of Petroleum Engineers (1999)
Google Scholar